PianoRollComposer uses the standard treble and bass clef staffs. Notes are displayed in the piano roll format (it shows music with absolute accuracy). Notes can be recorded as played, as well as entered directly on the staffs. A composition can contain music from either Windows sounds, SoundFont sounds, or VST sounds. PianoRollComposer can play and display any MIDI music. The music created with it can be played by any MIDI player. Music can be played on an 88-key Virtual Keyboard, along with one (or two) MIDI keyboard(s).
Music from different instruments is placed on the same staffs, using colors to differentiate them. Notes from different instruments can overlap on the staffs, which helps seeing the "big picture" of a composition. Instruments can be selected to be played and shown, or not. MIDI limits the number of instruments played and shown to 16 at a time, but using up to 32 VST plugins, up to 512 instruments can play and show at a time.
Play multiple instruments together with one keypress
(the instruments can be assigned pitch offsets from each other).
Record keyboard playing normally or using step-recording.
Step-recording allows multiple instruments to be recorded together.
Record to, play, edit, and mix WAVE files.
Music dynamics/special effects can be inserted/edited,
and they can be automatically added using step-recording.
A percussion loop window is available.
A chords/keys window is available.
A metronome beat is available.
You can add, delete, move notes, and change basic note types (and incrementally change note length). Groups of notes can be altered, deleted, copied, cut, moved, and transposed. Key and time signatures and beats/minute can be entered, changed, and displayed.
And much more.
I use it with EastWest's Hollywood Orchestra sampled instruments.

What is new in this release:

Version 2.57 may include unspecified updates, enhancements, or bug fixes.

What is new in version 2.56:

Version 2.56 may include unspecified updates, enhancements, or bug fixes.

What is new in version 2.55:

Version 2.55 may include unspecified updates, enhancements, or bug fixes.

What is new in version 2.53:

Version 2.53 may include unspecified updates, enhancements, or bug fixes.